/*
 * Copyright (C) 2012, 2016 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */

#pragma once

#include "ArrayConventions.h"
#include "Butterfly.h"
#include "IndexingHeader.h"
#include "include/JavaScriptCore/heap/MarkedSpace.h"
#include "SparseArrayValueMap.h"
#include "Structure.h"
#include "WriteBarrier.h"
#include <wtf/Noncopyable.h>

namespace JSC {

// This struct holds the actual data values of an array. A JSArray object points to its contained ArrayStorage
// struct by pointing to m_vector. To access the contained ArrayStorage struct, use the getStorage() and 
// setStorage() methods. It is important to note that there may be space before the ArrayStorage that 
// is used to quick unshift / shift operation. The actual allocated pointer is available by using:
//     getStorage() - m_indexBias * sizeof(JSValue)
// All slots in ArrayStorage (slots from 0 to vectorLength) are expected to be initialized to a JSValue or,
// for hole slots, JSValue().
    struct ArrayStorage {
    WTF_MAKE_NONCOPYABLE(ArrayStorage);
    private:
        ArrayStorage() {} // Not directly instantiable. Can only be created as part of a Butterfly.
    public:

        static ArrayStorage *from(Butterfly *butterfly) { return reinterpret_cast_ptr<ArrayStorage *>(butterfly); }

        static ArrayStorage *from(IndexingHeader *indexingHeader) { return indexingHeader->arrayStorage(); }

        Butterfly *butterfly() { return reinterpret_cast<Butterfly *>(this); }

        IndexingHeader *indexingHeader() { return IndexingHeader::from(this); }

        const IndexingHeader *indexingHeader() const { return IndexingHeader::from(this); }

        // We steal two fields from the indexing header: vectorLength and length.
        unsigned length() const { return indexingHeader()->publicLength(); }

        void setLength(unsigned length) { indexingHeader()->setPublicLength(length); }

        unsigned vectorLength() const { return indexingHeader()->vectorLength(); }

        void setVectorLength(unsigned length) { indexingHeader()->setVectorLength(length); }

        ALWAYS_INLINE void copyHeaderFromDuringGC(const ArrayStorage &other) {
            m_sparseMap.copyFrom(other.m_sparseMap);
            m_indexBias = other.m_indexBias;
            m_numValuesInVector = other.m_numValuesInVector;
        }

        bool hasHoles() const {
            return m_numValuesInVector != length();
        }

        bool inSparseMode() {
            return m_sparseMap && m_sparseMap->sparseMode();
        }

        ContiguousJSValues vector() { return ContiguousJSValues(m_vector, vectorLength()); }

        WriteBarrier<SparseArrayValueMap> m_sparseMap;
        unsigned m_indexBias;
        unsigned m_numValuesInVector;
#if USE(JSVALUE32_64)
        uintptr_t m_padding;
#endif
        WriteBarrier<Unknown> m_vector[1];

        static ptrdiff_t lengthOffset() { return Butterfly::offsetOfPublicLength(); }

        static ptrdiff_t vectorLengthOffset() { return Butterfly::offsetOfVectorLength(); }

        static ptrdiff_t numValuesInVectorOffset() { return OBJECT_OFFSETOF(ArrayStorage, m_numValuesInVector); }

        static ptrdiff_t vectorOffset() { return OBJECT_OFFSETOF(ArrayStorage, m_vector); }

        static ptrdiff_t indexBiasOffset() { return OBJECT_OFFSETOF(ArrayStorage, m_indexBias); }

        static ptrdiff_t sparseMapOffset() { return OBJECT_OFFSETOF(ArrayStorage, m_sparseMap); }

        static size_t sizeFor(unsigned vectorLength) {
            return ArrayStorage::vectorOffset() + vectorLength * sizeof(WriteBarrier<Unknown>);
        }

        static size_t totalSizeFor(unsigned indexBias, size_t propertyCapacity, unsigned vectorLength) {
            return Butterfly::totalSize(indexBias, propertyCapacity, true, sizeFor(vectorLength));
        }

        size_t totalSize(size_t propertyCapacity) const {
            return totalSizeFor(m_indexBias, propertyCapacity, vectorLength());
        }

        size_t totalSize(Structure *structure) const {
            return totalSize(structure->outOfLineCapacity());
        }

        static unsigned availableVectorLength(unsigned indexBias, size_t propertyCapacity, unsigned vectorLength) {
            size_t cellSize = MarkedSpace::optimalSizeFor(totalSizeFor(indexBias, propertyCapacity, vectorLength));

            vectorLength = (cellSize - totalSizeFor(indexBias, propertyCapacity, 0)) / sizeof(WriteBarrier<Unknown>);

            return vectorLength;
        }

        static unsigned availableVectorLength(unsigned indexBias, Structure *structure, unsigned vectorLength) {
            return availableVectorLength(indexBias, structure->outOfLineCapacity(), vectorLength);
        }

        unsigned availableVectorLength(size_t propertyCapacity, unsigned vectorLength) {
            return availableVectorLength(m_indexBias, propertyCapacity, vectorLength);
        }

        unsigned availableVectorLength(Structure *structure, unsigned vectorLength) {
            return availableVectorLength(structure->outOfLineCapacity(), vectorLength);
        }

        static unsigned optimalVectorLength(unsigned indexBias, size_t propertyCapacity, unsigned vectorLength) {
            vectorLength = std::max(BASE_ARRAY_STORAGE_VECTOR_LEN, vectorLength);
            return availableVectorLength(indexBias, propertyCapacity, vectorLength);
        }

        static unsigned optimalVectorLength(unsigned indexBias, Structure *structure, unsigned vectorLength) {
            return optimalVectorLength(indexBias, structure->outOfLineCapacity(), vectorLength);
        }

        unsigned optimalVectorLength(size_t propertyCapacity, unsigned vectorLength) {
            return optimalVectorLength(m_indexBias, propertyCapacity, vectorLength);
        }

        unsigned optimalVectorLength(Structure *structure, unsigned vectorLength) {
            return optimalVectorLength(structure->outOfLineCapacity(), vectorLength);
        }
    };

} // namespace JSC
